Aggressive Cutaneous Squamous Cell Carcinoma Research Articles

Spontaneous regression of aggressive cutaneous squamous cell carcinoma

Spontaneous regression of aggressive cutaneous squamous cell carcinoma

P37 Drug repurposing for treatment of recessive dystrophic epidermolysis bullosa cutaneous squamous cell carcinoma

Abstract Background Recessive dystrophic epidermolysis bullosa (RDEB) is an inherited skin disorder that leads to severe wounding and blistering of the skin. Patients with RDEB develop aggressive cutaneous squamous cell carcinoma (cSCC) with a mortality rate of approximately 90% by age 55 years. The current primary treatment is wide excision of tumours, often leading to amputations. Identifying new therapeutic avenues for RDEB cSCC remains a priority. Here, we approach this in two ways. Firstly, we identified a SMAD4-dependent sphingosine pathway response to endogenous transforming growth factor (TGF)-β, essential for RDEB cSCC proliferation which could be targeted as a potential therapeutic strategy. Secondly, we utilized a US Food and Drug Administration (FDA) screen of > 3000 drugs to identify potential druggable pathways that could be used to treat RDEB cSCC. Methods RDEB cSCC cell lines were used to test Siponimod, a sphingosine-1 receptor modulator, on proliferation, clonogenicity and invasion in vitro. Siponimod was used in vivo to test tumour growth effect of targeting the sphingosine pathway. We carried out an FDA-approved drug screen on four RDEB cSCC cell lines using the Opera Phenix high-throughput microscope to identify targets. Results Treatment of RDEB cSCC cell lines with Siponimod showed compromised proliferation compared with untreated cells in addition to significant reduction in colony formation. There was a significant decrease in the invasive capability of RDEB SCC cells. Treatment of normal human keratinocytes showed no effect on proliferation. Our FDA-approved screen identified multiple drugs that target MEK, mechanistic target of rapamycin complex, histone deacetylase, signal transducer and activator of transcription, and topoisomerase I/II in the top 50 hits. The most common target was DNA damage/repair pathways, but cytoskeletal signalling, transmembrane transporters and proteases were identified as other potential avenues for treatment of RDEB cSCC. Conclusions There is an unmet need for therapeutic options in RDEB cSCC. Here, we have demonstrated the potential of repurposing previously licensed drugs to identify treatment avenues for RDEB cSCC.

Metformin shows anti-neoplastic properties by inhibition of oxidative phosphorylation and glycolysis in epidermolysis bullosa-associated aggressive cutaneous squamous cell carcinoma.

While most cutaneous squamous cell carcinomas (cSCCs) are treatable, certain high-risk cSCCs, such as those in recessive dystrophic epidermolysis bullosa (RDEB) patients, are particularly aggressive. Owing to repeated wounding, inflammation and unproductive healing, RDEB patients have a 68% cumulative risk of developing life-threatening cSCCs by the age of 35, and a 70% risk of death by the age of 45. Despite aggressive treatment, cSCC represents the leading cause of premature mortality in these patients, highlighting an unmet clinical need. Increasing evidence points to a role of altered metabolism in the initiation and maintenance of cSCC, making metabolism a potential therapeutic target. We sought to determine the feasibility of targeting tumour cell energetics as a strategy to selectively hinder the growth advantage of aggressive cSCC. We evaluated the cell energetics profiles of RDEB-SCC cells by analysing available gene expression data against multiple gene signatures and single-gene targets linked to metabolic reprogramming. Additionally, we employed real-time metabolic profiling to measure glycolysis and respiration in these cells. Furthermore, we investigated the anti-neoplastic properties of the metformin against human and murine high-risk cSCCs in vitro and in vivo. Gene expression analyses highlighted a divergence in cell energetics profiles between RDEB-SCC and non-malignant RDEB keratinocytes, with tumour cells demonstrating enhanced respiration and glycolysis scores. Real-time metabolic profiling supported these data and additionally highlighted a metabolic plasticity of RDEB-SCC cells. Against this background, metformin exerted an anti-neoplastic potential by hampering both respiration and glycolysis, and by inhibiting proliferation in vitro. Metformin treatment in an analogous model of fast-growing murine cSCC resulted in delayed tumour onset and slower tumour growth, translating to a 29% increase in median overall survival. Our data indicate that metformin exerts anti-neoplastic properties in aggressive cSCCs that exhibit high-risk features by interfering with respiration and glycolytic processes.

Aggressive Cutaneous Squamous Cell Carcinoma of the Head and Neck: A Review.

Non-melanoma skin cancer of the head and neck (NMSCHN) is one of the most common malignancies worldwide, and its incidence is growing at a significant rate. It has been found to be aggressive in its spread and has the capacity to metastasize to regional lymph nodes. Cutaneous squamous cell carcinoma (cSCC) has a considerably high mortality rate. It has remarkable characteristics: diameter >2 cm, depth >5 mm, high recurrence, perineural invasion, and locoregional metastases. Aggressive cSCC lesions most commonly metastasize to the parotid gland. Also, immunocompromised patients have a higher risk of developing this aggressive cancer along with the worst prognostic outcomes. It is very important to discuss and assess the risk factors, prognostic factors, and outcomes of patients with cSCC, which will give clinicians future directives for making modifications to their treatment plans. The successful treatment of aggressive cSCC of the head and neck includes early detection and diagnosis, surgery alone or adjuvant chemotherapy, and radiotherapy as required. Multimodal therapy options should be considered by clinicians for better outcomes of aggressive cSCC of the head and neck.

P21 Tyrosine and serine STAT3 phosphorylation drives cutaneous squamous cell carcinoma in recessive dystrophic epidermolysis bullosa as demonstrated using a 3D in vitro model

Abstract The early onset of aggressive cutaneous squamous cell carcinoma (cSCC) and its rapid progression in recessive dystrophic epidermolysis bullosa (RDEB) leads to nearly 100% mortality rates in these patients. Elevated levels of phospho-STAT3 on tyrosine residue (STAT3Tyr705) have been intensively demonstrated in RDEB-derived cSCC cells, demonstrating that the constitutive activation and dysregulation of the Janus kinase (JAK)/STAT pathway plays a role in RDEB cSCC pathogenesis. We efficiently applied ruxolitinib (JAK1/2 inhibitor that blocks phosphorylation on STAT3Tyr705) to a RDEB–cSCC xenograph mouse model, reducing the size of small tumours but found that it was insufficient to reduce bigger tumours completely. Recently, phosphorylation at serine-727 (STAT3Ser727) has been shown to be relevant in the evolution of some cancers, but it has not yet been studied in RDEB cSCC. We hypothesized that phosphorylation at serine-727 of the STAT3 pathway might play a role in RDEB cSCC tumour development and progression, and could not be inhibited by ruxolitinib. To validate our hypothesis, we studied two RDEB cSCC human patient samples with different degrees of dedifferentiation (normal RDEB skin, edge of the tumour and centre of the RDEB cSCC). We demonstrated that STAT3Tyr705 was preferentially upregulated in the normal RDEB skin followed by the tumour edge skin, presenting less phosphorylation on the tumour. When we analysed STAT3 phosphorylation on STAT3Ser727, we could see that it presented the opposite phosphorylation pattern, being more phosphorylated in the tumour and less in normal RDEB skin. Furthermore, we validated the STAT3Ser727residue pattern across other cSCC cell lines and found that serine phosphorylation is present in other SCCs, demonstrating its crucial role in tumour development. To further investigate and analyse cancer progression in more detail, an easy and robust RDEB cSCC model is instrumental. Therefore, we generated RDEB cSCC spheroids in vitro, which has four key advantages over the previous models developed: (i) it is easy to generate; (ii) small amounts of cells are required; (iii) it is suitable for drug testing; and (iv) it can be used to recapitulate different stages of tumour development. We have been able to control their size and use them for drug testing, observing a 20% size decrease after 6 days of ruxolitinib treatment. Taken together, this three-dimensional RDEB cSCC in vitro model, along with analysis of human samples, will allow us to better understand RDEB cSCC progression at different stages, allowing us to investigate new treatments for RDEB cSCC.

445 Does tyrosine and serine phosphorylation of STAT3 drive cutaneous squamous cell carcinoma in recessive dystrophic epidermolysis bullosa?

The early onset of aggressive cutaneous squamous cell carcinoma (cSCC) and its rapid progression in recessive dystrophic epidermolysis bullosa (RDEB) leads to premature mortality. Elevated levels of STAT3Tyr705 (pY-STAT3) phosphorylation have been demonstrated in RDEB-derived cSCC cells, showing that constitutive activation and dysregulation of the pathway play a role in RDEB-cSCC pathogenesis. Application of Ruxolitinib (JAK1/2 inhibitor) to an RDEB-cSCC xenograph mouse model, reduces the size of small tumours but is insufficient to completely reduce bigger tumours.

Sulforaphane inhibits CD44v6/YAP1/TEAD signaling to suppress the cancer phenotype.

Sulforaphane (SFN) is a promising cancer prevention and treatment agent that strongly suppresses the cutaneous squamous cell carcinoma (CSCC) cell cancer phenotype. We previously showed that yes-associated protein 1 (YAP1)/TEAD signaling is a key procancer stimulator of the aggressive CSCC cell cancer phenotype. However, SFN-responsive upstream regulators of YAP1/TEAD signaling are not well characterized and so there is a pressing need to identify these factors. We show that CD44v6 knockdown reduces YAP1/TEAD-dependent transcription and target gene expression, and that this is associated with reduced spheroid formation, invasion and migration. CD44v6 knockout cell lines also display reduced YAP1/TEAD activity and target gene expression and attenuated spheroid formation, invasion, migration and tumor formation. An important finding is that SFN treatment suppresses CD44v6 level leading to a reduction in YAP1/TEAD signaling and marker gene expression. Sox2 level and epithelial-mesenchymal transition (EMT) are also reduced. Forced expression of constitutive active YAP1 in CD44v6 knockdown cells partially restores the aggressive cancer phenotype. These important findings suggest that CD44v6 drives YAP1/TEAD signaling to enhance the CSCC cell cancer phenotype and that SFN treatment reduces CD44v6 level/function which, in turn, reduces YAP1/TEAD signaling leading to reduced stemness, EMT and tumor growth.

34954 Cutaneous microbial markers of squamous cell carcinoma risk in solid organ transplant recipients

Solid organ transplant recipients (SOTRs) are 100-times more prone to aggressive cutaneous squamous cell carcinoma (SCC) compared with the general population. Despite this increased mortality, our ability to prognosticate risk of cancer in SOTRs is still poor. Accumulating evidence suggests a detrimental influence of microbial dysbiosis on transplant outcomes and immunosuppressant metabolism. Additionally, altered skin microbiome, specifically excessive colonization of the skin by Staphylococcus aureus, has been found in cutaneous SCCs of immunocompetent individuals. We hypothesized that cutaneous dysbiosis is a potential modifier to the risk of SCC in SOTRs and that the microbiome of SOTRs with a history of SCC (>4 instances) is distinct from the microbiome of SOTRs without a history of SCC. To investigate this theory, we generated microbial genomic data from the skin samples of 2 matched cohorts: SOTRs with and without history of SCC. Analyses included testing for differences in microbial diversity measures and differentially relatively abundant microbiome species between cohorts. In the cutaneous microbiomes of SOTRs with SCC history, we identified a significantly reduced abundance of Roseomonas mucosa, which is a S aureus–suppressive species. This suggests a protective effect of R mucosa against the development of SCC through suppression of a bacterial species hypothesized to initiate inflammation-related signaling involved in SCC-genesis. Overall, these findings not only point to a potential role of cutaneous microbiomes as predictive biomarkers for the development of SCC in SOTRs but also suggest that the microbiome can be used for potential preventive and interventional strategies.

Abstract 647: CXCL17 as a prognostic biomarker for aggressive cutaneous squamous cell carcinoma

Abstract Cutaneous squamous cell cancer (cSCC) is one of the most rapidly increasing cancers in the USA, striking 200,000 Americans annually. cSCC is most often observed in the sun-exposed areas such as the head and neck region. Although most patients have an improved prognosis after surgical treatment, a subset carries an increased risk of local recurrence, nodal metastasis, and disease-specific death. CXCL17 (C-X-C Motif Chemokine Ligand 17) is the latest chemokine family member, and our preliminary studies identified a causative role of CXCL17 in skin tumorigenesis. Accordingly, we aimed to investigate the correlation between CXCL17 and clinicopathological factors associated with recurrence, metastasis, and disease-specific death in cSCC. A retrospective chart review was conducted to identify patients with cSCC at Louisiana State University Health Sciences Center Shreveport (LSUHSC-S) and Overton Brooks Veterans Affairs Medical Center. Tissue samples were immunostained for human CXCL17/VCC-1. Risk factors such as the depth of invasion, perineural invasion, tumor diameter, location, and differentiation were obtained from chart review/clinical databases and correlated with the expression of CXCL17. Among 42 subjects included in the analysis, the Histo-score of CXCL17 expression in cytoplasm and nucleus was higher in the malignant group compared to the normal skin group (p=0.01 and p=0.03, respectively). Interestingly, the Histo-score of CXCL17 expression was associated with perineural invasion (p=0.01) suggesting a role for CXCL17 in disease aggressiveness. Our results indicate a positive correlation between CXCL17 and cSCC aggressiveness. Increased expression of CXCL17 was associated with perineural invasion, a principal risk factor for recurrence, metastasis, and disease-specific death in cSCC patients. These results suggest that CXCL17 plays a role as a prognostic marker and warrants further exploration as a potential target for treatment in aggressive cSCC. Citation Format: Janmaris Marin Fermin, Maksudul MD Alam, Xin Gu, Ameya Asarkar, Cherie-Ann Nathan, Alok R. Khandelwal. CXCL17 as a prognostic biomarker for aggressive cutaneous squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 647.

475 Targeting the JAK/STAT3 pathway with ruxolitinib for RDEB-cSCC therapy

The most lethal complication of recessive dystrophic epidermolysis bullosa (RDEB) is the development of aggressive cutaneous squamous cell carcinoma (cSCCs), which lead the high mortality rates in these patients. Elevated levels of phospho-STAT3 have been found in two RDEB-derived cSCC cell lines, demonstrating that constitutive activation and dysregulation of the JAK/STAT pathway may play a role in RDEB-cSCC pathogenesis. Ruxolitininb is an FDA approved JAK1/2 inhibitor that has efficacy in myelofibroblast, human head, and neck squamous cell carcinomas, as well as lung and breast carcinomas. However, its therapeutic effect has not been elucidated in RDEB-cSCC. Here, we investigated the in vivo pharmacological activity of ruxolitinib for locally advanced RDEB-cSCC treatment in a novel mouse xenograft model of RDEB-cSCC. We first built 3D cSCC skin constructs (SCs) using RDEB-cSCC and RDEB fibroblasts (FB), which were then grafted onto immunocompromised mice. The animals developed tumors within 4 weeks post-grafting, with characteristic morphological features of human RDEB-cSCC. We used this model to test ruxolitinib for its in vivo activity to reverse the accelerated tumor growth by oral and topical route of administration. We found that daily oral administration of 70 mg/kg ruxolitinib for 4 weeks has an inhibitory effect on tumor growth. Next, we exploited the ability of ruxolitinib to penetrate skin and its potency for inhibiting tumor growth via topical application. We observed that topical application of 2% ruxolitinib for 4 weeks has an inhibitory effect on smaller than 4 mm in dimeter tumor growth. Moreover, no toxicity or loss of body weight was observed during the treatment period. Taken together, we showed in vivo evidence of the therapeutic potential of ruxolitinib in RDEB-cSCC, thereby making ruxolitinib a promising anti-cancer drug against cSCC development and progression.

Correction: A Phase II Study of Gefitinib for Aggressive Cutaneous Squamous Cell Carcinoma of the Head and Neck.

Correction: A Phase II Study of Gefitinib for Aggressive Cutaneous Squamous Cell Carcinoma of the Head and Neck.

Phase 2 Trial of Adjuvant Concurrent Cetuximab and Radiation for High-Risk Cutaneous Squamous Cell Carcinoma of the Head and Neck

Aggressive cutaneous squamous cell carcinoma of the head and neck (CSCCHN) is most often treated with surgical resection followed by adjuvant radiation therapy (RT) with or without concurrent chemotherapy and locoregional control (LRC) remains problematic with 2 yr LRC of 60% to 80%. The addition of cytotoxic chemotherapy has not demonstrated benefit over adjuvant RT in randomized trials. NCT01979211 is a multi-institutional single arm phase 2 trial of concurrent adjuvant RT and cetuximab after primary surgical resection for CSCCHN. Eligibility criteria include high-risk (>N1, + PNI, bone or cartilage invasion) or locally recurrent CSCCHN after gross total resection. Primary endpoint is 2 yr LRC. Secondary endpoints include DFS, OS, acute and late toxicities (CTCAE v4.03), and patient reported quality of life with FACT-HN and Dermatology Life Quality Index (DLQI). Correlative studies include whole exome sequencing of primary tumor and nodal metastases. Twenty-three of planned 40 patients are accrued to date with a median 12 months of follow-up. Eighteen patients have completed all therapy per protocol with minimum 3-month follow-up. Of the patients, 91% were male, mean age 69 (range 50-80), all Zubrod 0-1. Of these, 18 patients, acute toxicities are as follows: 91% had grade 1 toxicities, mostly acneiform rash and mucositis, grade 2 reported in 61% patients including skin (39%), mucositis/oral pain (39%), fatigue (11%), allergic reaction (5%). Three patients had grade 3 skin toxicity, 1 patient had grade 3 mucositis. No grade 4 or 5 toxicities to date. Two patients developed locoregional failures, no one has developed distant metastases. 2 patients have died, 1 related to confirmed LRR. To date, mean baseline DLQI score is 5.5 (+/- 0.5) and at 3 mo post-RT is 3.9 (+/- 0.4), indicating a “small” improvement in skin QOL from postresection, preadjuvant therapy baseline. Mean baseline FACT- HN score is 120 (+/- 18) and 118 (+/- 25) at 3 mo post-RT. Postoperative concurrent cetuximab and RT for high risk CSCCHN appears well tolerated with favorable LRC thus far in comparison to institutional historic controls and quality of life scores comparable to other trials using concurrent cetuximab and RT for mucosal HNSCC.

Drug therapy of advanced cutaneous squamous cell carcinoma: is there any evidence?

There are few randomized controlled studies to guide the treatment of advanced cutaneous squamous cell carcinoma. The existing treatments are mostly based on case reports and small case series. Here we review recently available insights concerning the treatment of locally advanced and metastatic squamous cell carcinoma, with a special emphasis on novel targeted therapy and immunotherapy. Surgery and combination of chemotherapy and radiation therapy have been long considered the gold standard options for advanced squamous cell carcinoma. The detection of clinically relevant driver mutations has opened the door to the use of novel targeted therapies. Recent studies have shown that aggressive cutaneous squamous cell carcinoma is characterized by a very high mutational background. Furthermore, the importance of the defective immunosurveillance in the growth of cutaneous squamous cell carcinoma and the critical role of programed cell death protein 1 and programmed death-ligand 1 interaction in skin tumor development provides a rationale for the use of immune checkpoint inhibitors. Epidermal growth factor receptor inhibitors have shown to have satisfactory antitumor activity with acceptable side-effect profile. However, their place in management of advanced cutaneous squamous cell carcinoma alone or in combination with either radiation therapy and/or chemotherapy needs to be better characterized. The available preliminary findings suggest that immune checkpoint inhibitors represent a potentially valuable alternative in cutaneous aggressive squamous cell carcinoma, promising a further expansion of their indication spectrum. Randomized controlled studies will allow us to better characterize their practical value.

Focal Cutaneous Squamous Cell Carcinoma Following Radium-223 Extravasation

Long-term sequelae due to extravasation of intravenous radioisotopes resulting in radiation injuries are rarely reported. As the use of radioactive isotopes for the treatment of osteoblastic metastases increases, information regarding the prevention, treatment, and long-term monitoring of suspected extravasation injury will become increasingly important. We present a patient with no previous history of skin cancer who developed an aggressive cutaneous squamous cell carcinoma at the site of prior radium-223 extravasation. We recommend that patients who experience extravasation of therapeutic radioisotopes be monitored by dermatologists for long-term sequelae. Cutaneous squamous cell carcinoma should be recognized as a rare but potential adverse event following cutaneous extravasation of radium-223 and is likely a side effect that is severely underreported.

Interleukin-22 and Cyclosporine in Aggressive Cutaneous Squamous Cell Carcinoma.

Cutaneous squamous cell carcinomas (SCCs) account for up to 10,000 deaths annually in the United States. Most of the more than 700,000 SCCs diagnosed are cured by excision with clear margins; however, metastasis can occur despite seemingly adequate treatment in some cases. Immune-suppressed organ transplant recipients are 60 to 100 times more likely to develop SCC than immune-competent individuals. Transplant-associated SCCs occur more frequently and behave more aggressively, showing higher risk of recurrence and metastasis. This article identifies a potential role for interleukin-22 in driving SCC proliferation, particularly in solid organ transplant recipients taking cyclosporine.

Biomarker and Pathologic Predictors of Cutaneous Squamous Cell Carcinoma Aggressiveness.

Aggressive cutaneous squamous cell carcinoma (cSCC) patients are at increased risk of metastasis. Currently, there are no accepted criteria or biomarkers for reliably predicting individuals at risk for recurrence and metastasis. Our objective is to determine if pS6 and pERK can predict cSCC aggressiveness and to identify primary tumor characteristics that may predict parotid metastasis. Retrospective case series. Tertiary care center. An Institutional Review Board-approved retrospective review was performed for patients with facial cSCC, with and without metastasis to the parotids. Subjects for the study were identified through the Louisiana Tumor Registry, Veterans Medical Records, and LSU Health-Shreveport pathology database. Tumor specimens from patients with cSCC and cSCC with parotid metastasis were analyzed for pERK and pS6 expression through immunohistochemistry. To identify risk factors for tumor aggressiveness, multiple logistic regression analysis was used to evaluate patients with cSCC that was metastatic to the parotid and managed surgically. cSCC with parotid metastasis specimens exhibited significantly higher average pS6 but not pERK positivity than those from cSCC without metastasis (P < .05). Primary lesion-positive margins (P < .01), size of the skin tumor (P < .01) and degree of tumor differentiation (P < .01) were significantly associated with parotid metastasis. Surgical history of cSCC, primary lesion-positive margins, degree of differentiation, and lesion size together with pS6 positivity appear to be predictors of cSCC aggressiveness and should prompt increased monitoring or elective parotidectomy.

UV recall or inflammation of actinic keratoses? Post cetuximab reaction for a voriconazole induced aggressive cutaneous squamous cell carcinoma in a heart transplant patient

UV recall or inflammation of actinic keratoses? Post cetuximab reaction for a voriconazole induced aggressive cutaneous squamous cell carcinoma in a heart transplant patient

Inhibition of Akt Enhances the Chemopreventive Effects of Topical Rapamycin in Mouse Skin.

The PI3Kinase/Akt/mTOR pathway has important roles in cancer development for multiple tumor types, including UV-induced nonmelanoma skin cancer. Immunosuppressed populations are at increased risk of aggressive cutaneous squamous cell carcinoma (SCC). Individuals who are treated with rapamycin (sirolimus, a classical mTOR inhibitor) have significantly decreased rates of developing new cutaneous SCCs compared with those that receive traditional immunosuppression. However, systemic rapamycin use can lead to significant adverse events. Here, we explored the use of topical rapamycin as a chemopreventive agent in the context of solar-simulated light (SSL)-induced skin carcinogenesis. In SKH-1 mice, topical rapamycin treatment decreased tumor yields when applied after completion of 15 weeks of SSL exposure compared with controls. However, applying rapamycin during SSL exposure for 15 weeks, and continuing for 10 weeks after UV treatment, increased tumor yields. We also examined whether a combinatorial approach might result in more significant tumor suppression by rapamycin. We validated that rapamycin causes increased Akt (S473) phosphorylation in the epidermis after SSL, and show for the first time that this dysregulation can be inhibited in vivo by a selective PDK1/Akt inhibitor, PHT-427. Combining rapamycin with PHT-427 on tumor prone skin additively caused a significant reduction of tumor multiplicity compared with vehicle controls. Our findings indicate that patients taking rapamycin should avoid sun exposure, and that combining topical mTOR inhibitors and Akt inhibitors may be a viable chemoprevention option for individuals at high risk for cutaneous SCC.

Injury-Driven Stiffening of the Dermis Expedites Skin Carcinoma Progression.

Recessive dystrophic epidermolysis bullosa (RDEB) is a genetic skin fragility disorder characterized by injury-driven blister formation, progressive soft-tissue fibrosis, and a highly elevated risk of early-onset aggressive cutaneous squamous cell carcinoma (cSCC). However, the mechanisms underlying the unusually rapid progression of RDEB to cSCC are unknown. In this study, we investigated the contribution of injury-induced skin alterations to cSCC development by using a genetic model of RDEB and organotypic skin cultures. Analysis of RDEB patient samples suggested that premalignant changes to the dermal microenvironment drive tumor progression, which led us to subject a collagen VII hypomorphic mouse model of RDEB to chemical carcinogenesis. Carcinogen-treated RDEB mice developed invasive tumors phenocopying human RDEB-cSCC, whereas wild-type mice formed papillomas, indicating that the aggressiveness of RDEB-cSCC is mutation-independent. The inherent structural instability of the RDEB dermis, combined with repeated injury, increased the bioavailability of TGFβ, which promoted extracellular matrix production, cross-linking, thickening of dermal fibrils, and tissue stiffening. The biophysically altered dermis increased myofibroblast activity and integrin β1/pFAK/pAKT mechanosignaling in tumor cells, further demonstrating that cSCC progression is governed by pre-existing injury-driven changes in the RDEB tissue microenvironment. Treatment of three-dimensional organotypic RDEB skin cultures with inhibitors of TGFβ signaling, lysyl oxidase, or integrin β1-mediated mechanosignaling reduced or bypassed tissue stiffness and limited tumor cell invasion. Collectively, these findings provide a new mechanism by which RDEB tissue becomes malignant and offer new druggable therapeutic targets to prevent cSCC onset.

Abstract 4644: Curcumin C3 ® prevents ultraviolet B radiation-induced acute damage in JB6 keratinocytes and mouse skin via FGF-2/mTOR/NF-KB pathway

Abstract Background and Significance: Aggressive Cutaneous Squamous cell carcinoma (CSCC) of the face has become the second most common type of skin cancer in the USA due to ultraviolet B (UVB) exposure in tanning booths and sun exposure of our military personnel. UVB is a carcinogen and our previous studies established oral administration of Curcumin C3 complex (C3), a standardized preparation of three curcumonoids - Curcumin (76.07%), Demethoxycurcumin (20.28%) and Bisdemethoxycurcumin (3.63%), delayed UVB-induced tumor onset and multiplicity, but not tumor progression. Accordingly, we sort to determine the preventative efficacy of C3® against UVB-induced photodamage in promotion sensitive JB6 skin keratinocytes and SKH-1 hairless mouse epidermis on the early neoplastic events in the development of UVB-induced skin carcinogenesis. Methods: SKH-1 mice were either administered vehicle or C3 (100mg/kg/b.w) complex orally for 14 days followed by a single exposure to UVB radiation (180mj/cm2). Mice were euthanized 24 hours after UVB exposure and skin tissues and serum were collected. For in vitro studies, promoter-sensitive JB6 mouse epithelial cells were pre-treated with C3® for 2 h and the effects on UVB-induced early molecular signaling events were assessed. Results: C3® attenuated UVB-induced epidermal hyperplasia and significantly decreased epidermal and plasma levels of fibroblast growth factor-2 (FGF-2); an important mitogen implicated in proliferation and differentiation of skin keratinocytes. In vitro, C3®blocked UVB-dependent FGF-2 induction and proliferation of cultured keratinocytes via down regulation of nuclear factor kappa B (NF-KB) and Mammalian target of rapamycin (mTOR) signaling pathways. Conclusion: Our findings suggest C3® has the ability to protect mice from UVB-induced acute damage. Further the photo-preventive effects of C3® are mediated, at least in part, via modulation of FGF-2/mTOR/NF-KB signaling. Citation Format: Alok R. Khandelwal, Arun Anandharaj, Ekshyyan Oleksandr, Tara Moore-Medlin, Abreo Fleurette, Cherie-Ann O. Nathan. Curcumin C3 ® prevents ultraviolet B radiation-induced acute damage in JB6 keratinocytes and mouse skin via FGF-2/mTOR/NF-KB pathway. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4644. doi:10.1158/1538-7445.AM2015-4644